In order to realize magneto-optical recording with a higher content, a magnetic super-resolution reading system is proposed as a method of reading information recorded in a size not larger than an optical diffraction limit of light for reading (for example, JP-A-1-143041, JP-A-1-143042, etc.). (The term "JP-A" used herein means an unexamined and published Japanese patent application). In this method, at least a reading layer and a recording layer are used. Of a beam spot irradiated by reading light, a fixed area is used as a mask so as to obtain an effect substantially similar to that in the case where the beam spot is made smaller. This utilizes the fact that there is a distribution of intensity of light in the beam spot, and the fact that the temperature rising elevation is larger in the rear than in the front in the advancing direction of the beam.
As for such a method, there is a method using the fact that the reading layer is an in-plane magnetized film at room temperature so that information recorded in the recording layer is masked, and the reading layer becomes a perpendicularly magnetized film in an area where the temperature has reached or exceeded a predetermined value, so that the information recorded in the recording layer is transferred to the reading layer (for example, JP-A-5-81717). In this method, crosstalk with an adjacent track is very small because the reading layer is in the in-plane magnetization state also in the adjacent track.
According to this method, it is possible to reproduce bits recorded at a certain degree of narrower intervals than an optical diffraction limit of light for reading. However, there has been a problem that as the bit intervals are made to be narrower, the size of the bits becomes so small that the output is extremely lowered to thereby make the reading impossible.